Furnace hearth doors are currently constructed of cast iron shells rammed with a castable refractory. A cast iron mantle comprising many sections is bolted to the steel furnace outside frame and support beams to hold the door in place when closed. The furnace sidewall is constructed with a ramming or gunning refractory material such as Ram 80, manufactured by Plibrico Co. of Chicago, Illinois. The iron doors burn out and the castings warp and break up when the ramming material deteriorates and a loose fit results between the door and mantle. This condition allows heat to escape thereby escalating the deterioration of the furnace parts, and furthermore, increases fuel costs. The doors weigh in excess of 300 lbs. and in most cases must be opened by hand with a chain. It requires extensive mechanical and bricklayer repairs to keep the door working.